Construction of gasometer roof tanks



May 17, 1938.

E. H. STABER CONSTRUCTION OF GASOMETER ROOF TANKS Original Filed Jan.26, 1934 INVENTOR 46 M v, 4 I I I TORNEY Patented May 17, 1938 UNITEDSTATES PATENT OFFICE Ernest H. Staber, New York, N. Y., assignor toSocony-Vacuum Oil Company, Incorporated,

New York, N. Y., a corporation of New York Original application January26, 1934, Serial No. 708,351. Divided and this application August 18,1936, Serial No. 96,687

1 Claim.

This invention is directed to improvements in storage tanks for volatileliquids, and more particularly, is directed to improvements in tankshaving a gasometer type roof.

The gasometer roof tank is a tank in which the roof has a dependingskirt which dips into a trough extending around the circumference of thetank wall proper, either inside or outside, at the top. This trough orwell is fllled with liquid, and the tank roof is free to rise and sinkin accordance with the vapor pressure below. The application of excesspressure and vacuum is avoided by the use of proper relief valves.

Pressure and vacuum relief valves'of the type commonly supplied have notbeen properly applicable to the problems presented by gasometer rooftanks.

An object of this invention is .to provide a suitable relief valve forvacuum and pressure relief for use in connection with such tanks.

The various objects and, advantages are obtained by means of the designsset forth in this specification and shown in the drawing attached to andmade a part hereof.

Figure 1 of this drawing shows a vertical seci tion through the reliefvalves, and

Figure 2 shows a partial horizontal section taken at line 1-1 in Figure1.

\ To protect the tank against vacuum and .against pressures which mightnot be properly reilieved due to failure of operation of the roof, or

0 other causes, I make use of protective vacuum and pressure reliefvalves which are set forth diagrammatically in Figure 1. In this figure,

i represents a tank, having a gasometer type roof,

formed by a top 9 and a skirt 8 dipping into a liquid well 3-4, 28 and29 are valve chambers cylindrical in cross section, set up adjacent thetop of the tank wall in a convenient operating location, and at a heightsuch that they may communicate with each other through connection 30 andwith the dip ring trap on the tank wall through connection 3i, therebybeing filled with the same liquid as is used in the dip ring and beingsubjected automatically to the same conditions of dip ring level, etc.Chamber 28 is used for the release of pressure within the tank and isequipped with a vapor inlet 32 opening centrally into the bottom of thechamber 28. This vapor ing upward within chamber 28 to a level somewhatgreater than the level of the water overflow on the dipring trap. Overthis central pipe A 33 and surrounding it, there is placed a gasometerfloat 34 which extends in its normal position into inlet is surroundedby a circular pipe 33 extend the liquid in the vessel 28 to a depth ofsay 22 to 24 inches. This gasometer float 34 is made of a light weightmetal such as aluminum and its weight is adjusted by machining so thatit will rise and vent at the proper pressure. In other words; if the dipring vent is designed to operate at say 3 inches of water and it isdecided that the safety vent shall operate at flve inches of water, theweight of the gasometer float 34 is such that a pressure of five inchesof water exerted upon its area will lift it, allowing gas to escapeunder the bottom of its skirt. In the design of valves for use on tanksworking at high pressure, heavier metals, such as steel might be used.The skirt of this gasometer float 34 is provided with a plurality ofribs 35 which serve to guide it within chamber 28. Chamber 28 is open tothe atmosphere through an orifice 31 at its top, and is of sufficientheight to handle the full rise of gasometer float 34 and still retain itin position to properly return to its seat when through venting. Chamber28 is connected to the pressure space within the tank by inlet 32previously mentioned, and by pipe 38 which terminates within the tank ata point well up in the vapor space near the roof. For the relief ofvacuum, a similar chamber 29, equipped with a similar interior pipe 39and a similar gasometer float 40, is used, with the difference that inthis case the port 4| at the bottom of chamber 29 is open to theatmosphere, and the top of the chamber 28 is closed to the atmosphereand in communication with vent line 38. The gasometer float 40 hassimilar ribs 36 and in this case is machined so that its weight enablesit to act at the desired vacuum, which may for example be 1 of water, sothat when a vacuum greater than this amount exists within the tank, thegasometer float 48 will rise and air admitted through 4| will passupward through pipe 39, the gasometer float will rise to operatingposition, and the air will then pass downward around gasometer float40-, into chamber 29, and through pipe 38 into the vapor space of thetank. It is noted that this type of construction provides an unusuallylong liquid seal. Any of the usual devices for protecting a vent lineagainst the striking back will at once be apparent. In the past, reliefvalves of this type have been made so that they vented with acomparatively short rise and the rapidity with which they acted resultedin a considerable blowing of the sealing liquid. Many liquids have beenused as seals ranging from mercury through glycerine to water and lightpetroleum fractions. None of them have been eminently successful, yet aliquid seal valve is so much more desirable than one sealed bymechanical seating of the valve, that the type has persisted in spite ofits defects. These disadvantages 'I have avoided in several ways: First,I have eliminated the most frequently performed function, namely, thatof pressure venting for ordinary rises, and do not call upon the ventvalve to perform this routine venting, and reserve for it only the dutyof emergency relief, which can only occur when excessive binding takesplace between roof guides and rolls, (which condition should beimmediately corrected). Secondly, I have provided a vent valve on thegasometer principle, having a depth comparatively great in relation tothe necessary movement of the valve. For instance, in thepressure valveof the example cited, I have a 22 inch depth of seal to handle a fiveinch pressure variation, and consequently considerable blowing may takeplace before the liquid has been reduced to a depth where it will failto seal. Third, I may so place these liquid seals that they are alwaysin communication with and in a position to be replenished by theenormously larger reservoir of liquid in the dip ring seal, therebyassuring an ample supply-of liquid in seals of valves.

This case is a division of my copending application, Serial No. 708,351,filed January 26, 1934.

I claim:

In cooperation with a tank having a gasometer type roof, a pressurerelief 'valve and a vacuum relief valve, each comprising a liquid sealin open communication with the roof seal of the tank, and in each seal agasometer float valve, each valve of a predetermined weight to enablethe preselected pressure variation to cause it to rise and vent, eachvalve having a skirt of relatively great length compared to thedifference in sealing liquid levels at its venting position.

ERNEST H. STABER.

